Multi-path laser system
A laser chamber is provided that increases power, initiation, and discharge efficiency over single chamber lasers by providing a multi-fold laser chamber, protrusions, discharge segmentation and inversion techniques.
This application claims priority to provisional patents: application 60/535,549, filed 12 Jan. 2004, incorporated by reference in it's entirety; application 60/541,912, filed 6 Feb. 2004, incorporated by reference in it's entirety; application 60/544,198, filed 13 Feb. 2004, incorporated by reference in it's entirety; and application 60/605,157, filed 30 Aug. 2004, incorporated by reference in it's entirety.
FIELD OF THE INVENTIONThe invention relates in general to lasers and particularly but not exclusively to RF excited waveguide lasers.
BACKGROUND OF THE INVENTIONProblems exist in scaling low power RF-excited gas discharge lasers up to higher powers. The RF power distribution tends to become uneven over the discharge area and can concentrate in one spot, thereby disrupting what would otherwise have been a uniformly excited discharge suitable for efficient laser power extraction. Increasing power is achieved by increasing the gas gain volume that further requires increasing the volume of the laser discharge region. Because increasing discharge length also increases the discharge volume, and because low power RF-excited gas discharge lasers do not typically change in cross-section significantly, it is therefore convenient to speak of power scaling in terms of length scaling. Every one (1) cm increase in laser discharge length will result in an increase of laser output power of approximately 0.5 Watts. Some disadvantages of length scaling are a corresponding increase in the size of the laser, and an increase in the frequency of discharge instabilities and further risk of exceeding the intensity damage threshold of the laser mirrors.
Additionally many RF excited lasers form a sheath on the surface of the electrodes, both on the positive and ground electrodes. The sheath has a thickness that is significant enough to disturb or perturb the mode of the laser in the axis of the sheath. The mode disturbance or perturbation can result in oval beam outputs that are undesirable when trying to focus with a circular lens.
SUMMARY OF THE INVENTIONExemplary embodiments provide lasers that use multi-path (multi-fold) discharge chambers.
Exemplary embodiments provide lasers that use RF drive power inversion to improve mode quality.
At least one exemplary embodiment provides a multi-path waveguide laser chamber comprising: a first discharge chamber, the first discharge chamber including at least a first top electrode and a first bottom electrode; and a second discharge chamber, the second discharge chamber including at least a second top electrode and a second bottom electrode, where the first and second discharge chambers are aligned in a substantially parallel and nonlinear fashion, where at least two mirrors, a first mirror and a second mirror, are positioned to optically operatively connect the first and second discharge chambers.
At least one exemplary embodiment provides a laser chamber comprising: a first discharge chamber, where the first discharge chamber includes a first electrode and a second electrode; a second discharge chamber, where the second discharge chamber includes a third electrode and a fourth electrode; and at least one optical element, where the at least one optical element changes a beam's characteristics leaving the first discharge region before the beam enters the second discharge region. Where a further exemplary embodiment provides at least one optical element that rotates the beam's cross-section. In yet another exemplary embodiment the first and second discharge chambers are aligned in a linear fashion.
At least one exemplary embodiment provides a waveguide laser chamber comprising: a first discharge chamber, where the first discharge chamber includes a first electrode and a second electrode; and a second discharge chamber, where the second discharge chamber includes a third electrode and a fourth electrode, where a first plane passing substantially parallel through the first electrode makes an angle with a second plane passing substantially parallel through the third electrode.
At least one exemplary embodiment provides a method of RF inversion comprising: generating a first light in a first discharge chamber, where the first light leaves the first discharge chamber with a first cross-sectional orientation; coupling optically the first discharge chamber to a second discharge chamber, where the first light passes to the second discharge chamber; and rotating the first cross-sectional orientation into a second cross-sectional orientation prior to the first light entering a second discharge chamber.
Further areas of applicability of embodiments of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating exemplary embodiments of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.
BRIEF DESCRIPTION OF THE DRAWINGSEmbodiments of the present invention will become apparent from the following detailed description, taken in conjunction with the drawings in which:
The following description of exemplary embodiment(s) is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses.
Although the discussion herein may not discuss all details associated with multi-path and RF inversion laser systems, such details, as known by one of ordinary skill, are intended to be included within the scope of embodiments discussed herein.
Exemplary embodiments described herein are applicable for various laser systems with discharge regions, for example RF Excited Waveguide Gas (RFEWG) lasers, continuous wave or pulsed lasers, and other systems with discharge regions as known by one of ordinary skill.
To increase power without generally increasing laser size one can use multiple (at least two) discharge chambers. It is convenient to build multiple discharge sections that are optically connected. Using one mirror to interconnect multiple sections does not allow enough degrees of freedom to tilt and translate the beam from one discharge section to another. In exemplary embodiment two or more mirrors can be used to transfer the beam between discharge sections without altering the beam shape.
The electrodes are voltage driven by a power supply (e.g. Henry Radio model # SS750HF or other power supplies that provide power variation at frequencies as known by one of ordinary skill), along electrode feed cables (not shown), which are fed into the power inlet hole 240 in the insulating ring 260. In some exemplary embodiments the electrodes 270 are electrically connected via bridge 280. Additionally the electrodes 270 can be operatively connected to a grounded housing (not shown) via shunt inductors and conductive springs 230. The power supply chosen or made will depend upon the lasing medium (e.g. gas) and operating conditions, which can vary depending upon desired use.
The multi-path laser chamber 200 can include an end optical element 210 (e.g. mirror) at one end of the multi-path laser chamber 200 to reflect the light generated in discharge chambers back through the discharge chambers to an exit 290. The final optical element 250 directs the light through the final discharge chamber 205 to exit 290. The entire multi-path laser chamber can also be environmentally isolated (e.g. at a pressure other than atmospheric).
Although five discharge chambers are shown in
RF excited lasers form a sheath on the surface of the electrodes, both the positive and ground electrodes being excited. The sheath has a thickness that is significant enough to disturb or perturb the mode of the laser in the axis of the sheath. In one embodiment of the present invention, whether in a two or multiple path laser, the electrodes (and/or the excitation of the electrodes) can be rotated or flipped so that the sheath is rotated, and the mode disturbance is averaged in each axis. In a square bore (cross-section) system with an even number of passes, eg. 2, 4, 6, etc., the varying voltage is rotated at various angles (e.g. 90, 270 degrees) in the even numbered passes. In a circular bore system it can be more mechanically convenient to rotate the RF excitation, for example the RF excitation can be rotated angles other than 90 or 270. For example, in a three pass circular bore system the RF excitation electrodes can be be mounted at angles with 120 degrees rotation, or in a eight pass circular bore system the RF excitation electrodes can be mounted at angles with 45 degrees rotation. Although the examples provided discussed specific angular values, exemplary embodiments are not limited to the angular values specified, likewise exemplary embodiments are not limited to the number of passes (e.g. an odd or even number).
The RF drive power can be rotated (RF inversion) by rotating the angular RF position (e.g. rotating RF+ orientation from the first discharge chamber to the second discharge chamber of
In yet at least one further exemplary embodiment of RF inversion the cross section of the beam leaving one discharge chamber can be rotated using an optical element instead of, or in addition to an electrode rotation or RF rotation. For example in
As discussed, there are several methods of RF inversion that can be used in accordance with exemplary embodiments. In summary the two methods discussed include a method of RF inversion comprising: generating a first light in a first discharge chamber, where the first discharge chamber has a first orientation of a first electrode pair; generating a second light in a second discharge chamber, wherein the second discharge chamber has a second orientation of a second electrode pair; rotating the orientation of the first electrode pair with respect to the second electrode pair; and coupling optically the first discharge chamber to the second discharge chamber, wherein the first light passes to the second discharge chamber.
The second example discussed is a method of RF inversion comprising: generating a first light in a first discharge chamber, where the first light leaves the first discharge chamber with a first cross-sectional orientation; coupling optically the first discharge chamber to a second discharge chamber, where the first light passes to the second discharge chamber; and rotating the first cross-sectional orientation into a second cross-sectional orientation prior to the first light entering a second discharge chamber.
Other methods besides the two discussed here, that one of ordinary skill would know fall within the discussion herein, are intended to be within the scope of exemplary embodiments.
As discussed above exemplary embodiments can be used for all lasers. Waveguide lasers are defined by the gap between the electrodes that guides the mode of the laser. As the gap between the electrodes is opened up the laser is still RF driven but the waveguides do not guide the mode any more, so it is not a “waveguide” laser. A laser's Fresnel number defines a waveguide laser with any laser having a Fresnel number <<1 defined as a waveguide laser. Exemplary embodiments can be used with lasers with all possible associated Fresnel numbers.
The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the embodiments of the present invention. Such variations are not to be regarded as a departure from the spirit and scope of the present.
Claims
1. A multi-path waveguide laser chamber comprising:
- a first discharge chamber, the first discharge chamber including at least a first top electrode and a first bottom electrode; and
- a second discharge chamber, the second discharge chamber including at least a second top electrode and a second bottom electrode, where the first and second discharge chambers are aligned in a nonlinear fashion, wherein there are at least two mirrors: a first mirror; and a second mirror, wherein the first mirror and the second mirror are positioned to optically operatively connect the first and second discharge chambers.
2. The waveguide laser chamber of claim 1, further comprising:
- at least one optical element, wherein the at least one optical element rotates the cross-section of a beam leaving the first discharge chamber prior to entering the second discharge chamber
3. The waveguide laser chamber of claim 1, wherein the first and second discharge chambers are positioned so that a first plane passing through the first upper electrode intersects at an angle a second plane passing through the second upper electrode, where an angular RF orientation rotates from the first discharge chamber to the second discharge chamber.
4. The waveguide laser chamber of claim 1, wherein the two upper electrodes are electrically connected.
5. The waveguide laser chamber of claim 1, further comprising:
- a planar mirror, wherein the planar mirror is placed to reflect light leaving one end of one of the first discharge chamber reflecting at least a portion of the light back into the first discharge chamber.
6. The waveguide laser chamber of claim 1, further comprising:
- a third mirror, wherein the third mirror directs light from the first discharge chamber into the second discharge chamber.
7. The waveguide laser chamber of claim 3, wherein the angle is substantially 90 degrees.
8. The waveguide laser chamber of claim 6, wherein the light directed from the third mirror passes through the second discharge chamber and exits the laser chamber forming a laser beam.
9. A waveguide laser chamber comprising:
- a first discharge chamber, wherein the first discharge chamber includes a first electrode and a second electrode; and
- a second discharge chamber, wherein the second discharge chamber includes a third electrode and a fourth electrode, wherein a first plane passing substantially parallel through the first electrode makes an angle with a second plane passing substantially parallel through the third electrode, where an angular RF orientation rotates from the first discharge chamber to the second discharge chamber.
10. The waveguide laser chamber of claim 9, wherein the first and second discharge chambers are aligned in a linear fashion.
11. A laser chamber comprising:
- a first discharge chamber, wherein the first discharge chamber includes a first electrode and a second electrode;
- a second discharge chamber, wherein the second discharge chamber includes a third electrode and a fourth electrode; and
- at least one optical element, wherein the at least one optical element rotates the cross-section of a beam leaving the first discharge chamber prior to entering the second discharge chamber.
12. The laser chamber of claim 11, wherein the first electrode has a protrusion.
13. The laser chamber of claim 11, wherein the first electrode is segmented.
14. A waveguide laser chamber comprising:
- power means, where the power means provides voltage at a frequency;
- first discharge chamber means, wherein the first discharge chamber means has a first pair of electrodes and generates a first light when voltage driven by the power means;
- second discharge chamber means, wherein the second discharge chamber means has a second pair of electrodes and generates a second light when voltage driven by the power means, where the second discharge chamber means and the first discharge chamber means are arranged nonlinearly and substantially parallel; and
- optical coupling means, wherein the optical coupling means transfers the first light from the first discharge chamber means to the second discharge chamber means, and transfers the second light from the second discharge chamber means to the first discharge chamber means.
15. A laser chamber comprising:
- power means, where the power means provides voltage at a frequency;
- first discharge chamber means, wherein the first discharge chamber means has a first pair of electrodes and generates a first light when voltage driven by the power means;
- second discharge chamber means, wherein the second discharge chamber means has a second pair of electrodes and generates a second light when voltage driven by the power means; and
- RF inversion means, wherein the RF inversion means rotates the angular RF position.
16. The laser chamber of claim 15, wherein the inversion means rotates the angular RF position by rotating the first pair of electrodes with respect to the orientation of the second pair of electrodes.
17. The laser chamber of claim 15, wherein the inversion means rotates the angular RF position by using an optical element that rotates the cross-section of a beam leaving the first discharge chamber prior to entering the second discharge chamber.
18. The laser chamber of claim 15, further comprising:
- discharge initiation means, wherein the discharge initiation means initiates a discharge at a portion of an electrode.
19. The laser chamber of claim 15, further comprising:
- segmentation means, wherein the segmentation means segments the discharge of the first electrode.
20. A method of RF inversion comprising:
- generating a first light in a first discharge chamber, wherein the first light leaves the first discharge chamber with a first cross-sectional orientation;
- coupling optically the first discharge chamber to a second discharge chamber, wherein the first light passes to the second discharge chamber; and
- rotating the first cross-sectional orientation into a second cross-sectional orientation prior to the first light entering a second discharge chamber.
Type: Application
Filed: Jan 12, 2005
Publication Date: Jul 14, 2005
Patent Grant number: 7577177
Inventor: Nathan Monty (Charlton, MA)
Application Number: 11/033,495